Inter-device I/O (input/output) allows different system components to communicate to each other for operation of modern computing systems that find their use in any of a very wide array of consumer and commercial devices. Improvements in device operation and minimum geometry scaling have enabled devices to become more energy efficient. Consequently, inter-device I/O or inter-device communication or I/O is a significant factor in the power consumption of the operation of many electronic devices. To improve inter-device I/O power performance, many systems reduce the transfer of I/O clocks or timing signals between devices. To maintain adequate I/O error performance, various techniques can be used to provide phase compensation of the I/O signals.
One type of phase compensation (such as that used in certain double data rate (DDR) memory I/O delay locked loops (DLLs)) is a serial type of delay chain. A serial type delay chain first performs a coarse lock, and then performs a fine delay lock in series. Serial type delay chains cause switching jitter during DLL tracking or phase locking. The jitter introduced by serial delay chains can be reduced by use of a parallel type of delay chain. Parallel type delay chains perform fine delay mixing of the coarse locking. However, parallel type delay chains can still introduce jitter if the DLL delay chain coarse code and fine code are switched at the same time. Such jitter can be effectively removed by implementing triangular controlled fine delay mixing. However, traditional triangular control is generated by complex circuits and/or state machines. The complexity increases the amount of logic used. Known designs for triangular control include shift register circuits, which result in complicated logic control. Additionally, shift register circuits are known to introduce timing errors.
Descriptions of certain details and implementations follow, including a description of the figures, which may depict some or all of the embodiments described below, as well as discussing other potential embodiments or implementations of the inventive concepts presented herein.